Scientists from the NASA Obsevatory in the month of May 2013 have found that magnetars — the dense remains of dead stars that erupt periodically with bursts of high-energy radiation may be more diverse and common than earlier considered.
It is found that when a massive star runs out of fuel, its core collapses to form a neutron star, which is an ultra-dense object about 16 to 24 kilometres wide. The gravitational energy released in this process blows the outer layers away in a supernova explosion and leaves the neutron star behind.
Most magnetars have extremely high magnetic fields on their surface that are ten to a thousand times stronger than for the average neutron star.
As per the observations it was show that the magnetar known as SGR 0418+5729 (SGR 0418 for short) does not fit that pattern. It has a surface magnetic field similar to that of mainstream neutron stars.
The researchers monitored SGR 0418 for over three years using Chandra, ESA’s XMM-Newton as well as NASA’s Swift and RXTE satellites.
They were able to make an accurate estimate of the strength of the external magnetic field by measuring how its rotation speed changes during an X-ray outburst.
These outbursts are likely caused by fractures in the crust of the neutron star precipitated by the buildup of stress in a relatively strong, wound-up magnetic field lurking just beneath the surface.
What are Neutron Stars?
A neutron star is a very small and dense star made up of almost completely of neutrons. It is a very large nucleus held together by gravity. It has a radius of about 10 kilometres (6 mi) and a mass from about 1.4 to 5 times the mass of the Sun.
They are usually what is left of very big stars that have exploded (these are called supernovas). Some are what happen to white dwarfs (small stars) that have got a lot of extra mass.Neutron stars usually turn very fast, taking from 0.001 second up to 30 seconds to turn.
Most neutron stars are spinning rapidly — a few times a second — but a small fraction have a relatively low spin rate of once every few seconds, while generating occasional large blasts of X-rays.